University of Maryland Extension

Eastern/Forest Tent Caterpillars - Trees

caterpillars in webbing
Eastern tent caterpillars

Eastern tent caterpillar is a common pest of wild cherry trees in the spring. Eggs are contained in 1-inch long, black, gall-like masses on slender twigs of wild cherry trees. Eggs generally hatch around the first week of April. Young caterpillars are black. They spin silk tents in branches. The caterpillars enlarge the tents as they grow. Mature caterpillars have a white stripe down the back. Most feeding damage is done in May. Preferred host trees in addition to wild cherry include crabapple and apple. Forest tent caterpillar has a similar life cycle. It prefers to feed on deciduous shade trees and flowering fruit trees. These caterpillars have oval white spots down the back and do not construct tents.

 black egg mass wrapped around twig
Eastern tent caterpillar egg mass 
(easier to find on host trees in the winter)

forest and eastern tent caterpillars
Forest Tent Caterpillar (top) and 
Eastern Tent Caterpillar (bottom)

mature eastern tent caterpillar on a rose shrub
Mature tent caterpillar on a rose
looking for a place to pupate. At this
stage in their life-cycle they are not
causing feeding damage

Management

Most often control is not necessary. Once the caterpillars leave the tent they are picked up by birds to feed their young or by other insect-eaters.

Prune out egg masses (see photo above) during the fall, winter or early spring, and destroy them or leave them in a place accessible to birds.  Manually destroy the webs and caterpillars in the evening (when they are back in the tent) during April. If an insecticide application is needed, use Bt (Bacillus thuringiensis) when the caterpillars are small and make sure to penetrate the tents with the spray. 

Additional Information

(PDF) HG21 Eastern and Forest Tent Caterpillars

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